Efficient Network Reachability Analysis Using a Succinct Control Plane Representation

12th USENIX Symposium on Operating Systems Design and Implementation (OSDI 2016), Savannah, GA, November 2-4, 2016.
Seyed K. Fayaz, Tushar Sharma, Ari Fogel, Ratul Mahajan, Todd Millstein, Vyas Sekar, George Varghese
To guarantee network availability and security, operators must ensure that their reachability policies (e.g., A can or cannot talk to B) are correctly implemented. This is a difficult task due to the complexity of network configuration and the constant churn in a network's environment, e.g., new route announcements arrive and links fail. Current network reachability analysis techniques are limited as they can only reason about the current "incarnation" of the network, cannot analyze all configuration features, or are too slow to enable exploration of many environments. We build ERA, a tool for efficient reasoning about network reachability. Instead of reasoning about individual incarnations of the network, ERA directly reasons about the network "control plane" that generates these incarnations. We address key expressiveness and scalability challenges by building (i) a succinct model for the network control plane (i.e., various routing protocols and their interactions), and (ii) a repertoire of techniques for scalable (taking a few seconds for a network with > 1000 routers) exploration of this model. We have used ERA to successfully find both known and new violations of a range of common intended polices.

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